A sign warning of asbestos in a building is placed over a stop sign...

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Treasure Island resident Kathryn Lundgren stands in front of her home on Treasure Island on Monday, March 24, 2014, on Treasure Island in San Francisco, Calif. A group of Navy contractors dug a small radioactive fragment out of her front yard in January 2014.

Treasure Island resident Kathryn Lundgren holds a piece of material with, what Lundgren believes to be, asbestos on it that she collected while walking on Treasure Island on Monday, March 24, 2014, on Treasure Island in San Francisco, Calif. Lundgren believes there is asbestos on this sample but it has not been tested yet. A group of Navy contractors dug a small radioactive fragment out of her front yard in January 2014.

Quinn Lundgren (l to r), talks with her parents Kathryn Lundgren and Eric Lundgren on a day she had to stay home sick from school on Friday, November 1, 2013 on Treasure Island in San Francisco, Calif.

The U.S. Navy will test all of the homes on Treasure Island for elevated radiation levels in response to increasing public concern over the island's safety after the discoveries in recent years of radioactive items buried near housing.

The Navy, which has repeatedly insisted that the island is safe, said in a statement Monday that authorities still believe there are "no known health hazards," but it decided to conduct radiological surveys underneath and inside all the occupied housing units "due to a recent radiological finding beneath an (empty) housing unit," as well as requests from residents.

It's not clear what recent radiological finding the Navy is referring to. In January, Navy contractors dug a small radioactive fragment out of the ground in front of a home occupied by Kathryn Lundgren, her husband and their three teenage children.

That was the latest in a string of radiological discoveries over the past seven years revealed by state and federal officials in charge of cleaning up the former military base, which will eventually be transferred to the city of San Francisco and redeveloped.

A year ago, two other fragments with elevated radiation levels were dug up near Lundgren's home.

"The Navy cares about the people who live and work on Treasure Island and is committing to protecting human health and the environment," said Keith Foreman, the Navy's base realignment and closure environmental coordinator for the Treasure Island project.

The Navy said it is notifying residents about the new tests and will hold an informational meeting for residents.

Working out protocols

Bob Beck, who oversees the city's development efforts at the Treasure Island Development Authority, said the Navy hasn't set a timeline for the tests, but it won't be immediate because the military still has to work out protocols with state health regulators, tackle access issues with the city and its housing providers, and hire a contractor to conduct the work.

The city still has several procedural questions about how the testing will be conducted, he said. City officials have been assured that residents will be able to stay in their homes while the testing is conducted, Beck said.

"Our understanding is that they will be conducting surveys of the (concrete) slabs under buildings ... to assess whether there might be materials beneath and if so what exposure it could represent," he said. "We are glad the Navy is taking this step ... to provide some assurances and certainty to residents."

Critics have questioned whether the city should have moved people onto the island in the first place. While the Navy knew it would need to undertake an environmental cleanup before the island could be developed, the military and city of San Francisco didn't wait for that cleanup to be completed before moving people there: About 2,000 families have lived in former military housing on the island and nearby Yerba Buena Island since 1999.

The Navy didn't publicly acknowledge that there was radiological contamination until 2007 but has long known about other contaminants in the housing area, including asbestos and lead paint in the half-century-old homes and the arsenic, pesticides, lead, PCBs and other chemicals left over in the soil from when the housing area was used as a trash pit.

Worried about losing home

Lundgren, who has been vocal about her concerns over the island's safety and her family's chronic health problems since moving there in 2006, said she is glad the Navy is starting to take the public's fears more seriously. But Lundgren said she is worried the testing or its outcomes will be used by city officials as an excuse to push residents - many of them low-income - off the island without any financial assistance.

"That sounds like a precursor to us having to move off here - how can they do that underneath our (homes) without removing us from the area?" she asked. "I am glad they are doing the testing. ... I'm frustrated it's taken this long."

Lundgren said city and state officials who have overseen the cleanup and the Navy "need to be investigated."

"If they know all this now, they should have known it 10 years ago," she said.

The Navy said the radiation is left over from the decontamination of radioactive ships and from dials, gauges and deck markers left behind from a time when the military used radioactive paint to make objects glow in the dark.